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中国农学通报

中国农学通报 ›› 2014, Vol. 30 ›› Issue (35): 220-226.doi: 10.11924/j.issn.1000-6850.2014-1304

所属专题： 农业气象

• 资源 环境 生态 土壤 气象 • 上一篇    下一篇

高低空急流在一次暴雨过程中的动力作用

全美兰   

  1. 辽宁省抚顺市气象局
  • 收稿日期:2014-05-06 修回日期:2014-12-21 接受日期:2014-07-23 出版日期:2015-03-18 发布日期:2015-03-18
  • 通讯作者: 全美兰
  • 基金资助:
    辽宁省气象局科研课题“抚顺近10 年暴雨雪的短期预报研究”(201113)

The Dynamic Action of Upper-level and Lower-level Jet Stream in Liaoning Regional Rainstorm

  • Received:2014-05-06 Revised:2014-12-21 Accepted:2014-07-23 Online:2015-03-18 Published:2015-03-18

摘要： 利用常规台站降水资料和NCEP/NCAR一日四次的1°×1°再分析资料，使用天气动力学诊断方法，分析了高低空急流及其次级环流在辽宁2010年8月4至5日区域性暴雨过程中的动力作用。结果表此次暴雨过程发生在“东高西低”的大尺度环流形势下，强降水发生在584~588 dagpm 等值线之间，主要影响系统是高空槽、副热带高压外围西南气流和切变线。在暴雨过程中，高空急流的加强东移对低空急流加强和发展起着重要的作用，也是辽宁东部低空急流加强和发展的重要动力原因。辽宁东部的低空急流的北侧上升支刚好位于暴雨区上空，为暴雨过程提供了有利的动力条件。暴雨区出现在200hPa 高空急流入口区右侧、850hPa 西南低空急流左侧。高空急流入口区北侧上升，南侧下沉的次级环流圈是本次暴雨的独特特征。在高空急流强盛期间，影响暴雨区的次级环流是反环流圈，即在辽宁上升，在辽宁以南地区下沉；而在降水后期，随着高空急流减弱，快速东移，由辽宁东部低空急流北侧的上升支，与辽宁以北的西北风低空急流的南侧的下沉支形成正环流。本次过程中低空形成两支急流，且低空急流的次级环流恰好镶嵌在高空急流的次级环流中，次级环流的方向转变均是本次暴雨过程中的重要特征。

关键词: 预测, 预测

Abstract: Based on the data of conventional observation and the NCEP reanalysis, the author used weather dynamic diagnosis methods to analyze the dynamic processes of upper- level and lower- level jet stream for Liaoning regional rainstorm on 4th- 5th August 2010. The results showed that the heavy rain occurred in the large-scale circulation situation of“East West”，the heavy rainfall occurred between the line of 584 dagpm and 588 dagpm, and the main impact system were the upper trough, the subtropical high and low-level shear line. In heavy rainfall, the upper- level jet stream’s eastward movement played an important role in the development and strengthening of the low-level jet, and could be the important driving force that caused the formation of the LLJ in Liaoning Province. The heavy rainfall occurred at the right side of entrance region of the upper-level jet and the left side of entrance region of the lower-level jet. During heavy rainfall, the descending motions occurred in the north side of the upper-level jet stream, but the sink motion occurred in the southern of the entrance area. It was noteworthy that during rainstorm, there were two low-level jets at 850 hPa, while the ascending branch of the low-level jet provided favorable dynamic conditions. The southerly moving of the sinking branch of the lower-level jet stream provided a favorable moisture conditions. During the powerful jet stream, the secondary circulation which affected rainstorm area was anti-circulation loop that ascending in the Liaoning Province and sinking in the southern of Liaoning Province; in the late stage, along with the jet stream weakened rapidly, the ascending branch of the low-level jet was in the southern of Liaoning province and the sinking branch of the low-level jet in northern Liaoning Province, which formed a Positive circulation. In this process, the presence of two low-level jet streams, the low-level jet secondary circulation just embedded in the high-altitude jet secondary circulation and the conversion of the direction of the secondary circulation were all important features of the heavy rain.